Babies tend to come off the teat when they’ve had enough, even during sleep
Similar to Sonia, even though my boys asleep whilst having a bottle he knows when he’s had enough and will pull away from the teat. I wouldn’t force him to have more just because he may of had a little bit. They tend to know when enough is enough and for them to be content x
I'm breastfeeding so not 100% sure if it's any different but my LO falls asleep on the boob regularly but he continues sucking until he chooses to stop. I'd assume that it's the same - your wee one will remove themselves from the bottle when they are done, even when sleeping.